Method of cleaning stage in plasma processing apparatus, and the plasma processing apparatus

Abstract

A method of cleaning a stage in a plasma processing apparatus including the stage on which a substrate is placed, a lifting mechanism configured to raise and lower the substrate with respect to the stage, and a high-frequency power supply connected to the stage, includes: separating the stage and the substrate from each other using the lifting mechanism; and after the separating the stage and the substrate from each other, removing a deposit deposited on the stage with plasma generated by supplying a high-frequency power from the high-frequency power supply to the stage. In the separating the stage and the substrate from each other, a separation distance between the stage and the substrate is set such that a combined impedance formed around an outer peripheral portion of the stage is lower than a combined impedance formed immediately above a central portion of the stage.

What is claimed is: 
     
       1. A plasma processing apparatus, comprising:
 a processing container having a loading/unloading port for a substrate, a gas inlet and a gas exhaust port; 
 a stage disposed in the processing container; 
 a lifter pin which raises and lowers with respect to a position of the stage; 
 a plasma generator to generate plasma in the processing container; 
 a memory which stores a predetermined separation distance between a dummy substrate and a placement surface of the stage; and 
 controller circuitry configured to, following a plasma processing of the substrate in the processing container:
 control for the substrate to be unloaded from the processing container through the loading/unloading port; 
 control the plasma generator to generate a first plasma, from a first cleaning gas supplied through the gas inlet into the processing container, to clean the processing container; 
 control the lifter pin to raise to receive the dummy substrate at a first position above the stage, after the dummy substrate is loaded into the processing container through the loading/unloading port; 
 
 control the lifter pin to locate the dummy substrate at a second position that is the predetermined separation distance lower than the first position; and
 control the plasma generator to generate a second plasma, from a second cleaning gas supplied through the gas inlet into the processing container, to clean the processing container. 
 
 
     
     
       2. The plasma processing apparatus of  claim 1 , wherein the controller circuitry is further configured to, after unloading the substrate from the processing container and cleaning the processing container with the second plasma:
 control the lifter pin to lower to place the dummy substrate on the placement surface of the stage; and 
 control the plasma generator to generate a third plasma in the processing container. 
 
     
     
       3. The plasma processing apparatus of  claim 1 , wherein cleaning of the processing container removes deposits generated at an outer peripheral portion of the stage during the plasma processing of the dummy substrate with the first and second plasmas. 
     
     
       4. The plasma processing apparatus of  claim 1 , wherein the plasma processing comprises plasma etching. 
     
     
       5. The plasma processing apparatus of  claim 1 , wherein the plasma generator further comprises a high-frequency power supply electrically coupled to the stage. 
     
     
       6. The plasma processing apparatus of  claim 1 , wherein the second plasma generated from the second cleaning gas has a ring shape. 
     
     
       7. The plasma processing apparatus of  claim 1 , wherein the predetermined separation distance is between 2.3 mm and 5 mm. 
     
     
       8. The plasma processing apparatus of  claim 1 , wherein the second cleaning gas includes an oxygen-containing gas. 
     
     
       9. The plasma processing apparatus of  claim 1 , wherein cleaning of the processing container with the first plasma is performed after the substrate is unloaded from the processing container and before the dummy substrate is loaded into the processing container. 
     
     
       10. The plasma processing apparatus of  claim 1 , wherein cleaning of the processing container with the second plasma is performed with the dummy substrate remaining in the processing container. 
     
     
       11. The plasma processing apparatus of  claim 1 , wherein the predetermined separation distance is smaller than a thickness of a sheath of the second plasma. 
     
     
       12. The plasma processing apparatus of  claim 1 , wherein a density of the second plasma is greater around an outer peripheral portion of the dummy substrate than in a central portion of the dummy substrate. 
     
     
       13. The plasma processing apparatus of  claim 12 , further comprising a focus ring member surrounding an outer periphery of a placement surface of the stage. 
     
     
       14. The plasma processing apparatus of  claim 13 , wherein the density of the second plasma is greater in an inner peripheral portion of the focus ring member than in an outer peripheral portion of the focus ring member. 
     
     
       15. The plasma processing apparatus of  claim 14 , wherein the focus ring member comprises single-crystal silicon. 
     
     
       16. The plasma processing apparatus of  claim 1 , wherein the cleaning of the processing container with the first plasma is performed after the unloading of the substrate from the processing container and before the loading of the dummy substrate into the processing container. 
     
     
       17. A plasma processing apparatus, comprising:
 a processing container having a loading/unloading port for a substrate, a gas inlet and a gas exhaust port; 
 a stage disposed in the processing container; 
 a lifter pin; 
 a lifting mechanism for raising and lowering the lifter pin with respect to a position of the stage; 
 a plasma generator to generate plasma in the processing container; 
 a memory which stores a predetermined separation distance between a dummy substrate and a placement surface of the stage; and 
 controller circuitry configured to, following a plasma processing of the substrate in the processing container:
 control the lifting mechanism to unload the substrate from the processing container; 
 control the plasma generator to generate a first plasma, from a first cleaning gas supplied through the gas inlet into the processing container, to clean the processing container; 
 control the lifting mechanism to raise the lifter pin to receive the dummy substrate at a first position above the stage, after the dummy substrate is loaded into the processing container through the loading/unloading port; 
 control the lifting mechanism to locate the dummy substrate at a second position that is the predetermined separation distance lower than the first position; and 
 control the plasma generator to generate a second plasma, from a second cleaning gas supplied through the gas inlet into the processing container, to clean the processing container.